Energy Transfer and Scintillation Properties of ${\hbox {Ce}}^{3+}$ Doped ${\hbox {(LuYGd)}}_{3}$

Photoluminescence, X-ray excited radioluminescence and photoelectron yield characteristics were studied in multicomponent GdGaYAG:Ce and GdGaLuAG:Ce garnet films grown by liquid phase epitaxy. Nonradiative energy transfer from Gd³⁺ to activator Ce³⁺ ions was evidenced. At low Gd doping, , two virtually independent emission centers coexist, which compete for intensity: Ce³⁺ with fast 5d-4f emission and Gd³⁺ with slow 4f-4f emission. At higher Gd concentrations, the Ce³⁺ emission retrieves intensity due to the energy transferred from Gd³⁺ donors. At Gd concentration ~ 50% and above, the Gd³⁺ emission is suppressed due to energy migration and transfer to Ce³⁺ centers. In these samples, the host emission is also completely quenched and the best scintillator performance is achieved. Contrary to melt-grown crystals, no positive role of Ga substitution was found in epitaxial films.